title: Water flux through human aquaporin 1: inhibition by intracellular furosemide and maximal response with high osmotic gradients.
abstract: This work studies water permeability properties of human aquaporin 1 (hAQP1) expressed in Xenopus laevis oocyte membranes, applying a technique where cellular content is replaced with a known medium, with the possibility of measuring intracellular pressure. Consequences on water transport-produced by well-known anisotonic gradients and by the intracellular effect of probable aquaporin inhibitors-were tested. In this way, the specific intracellular inhibition of hAQP1 by the diuretic drug furosemide was demonstrated. In addition, experiments imposing anisotonic mannitol gradients with a constant ionic strength showed that the relationship between water flux and the applied mannitol gradient deflects from a perfect osmometer response when the gradient is higher than 150 mosmol kg (W) (-1) . These results would indicate that the passage of water molecules through hAQP1 may have a maximum rate. As a whole, this work demonstrates the technical advantage of controlling both intracellular pressure and medium composition in order to study biophysical properties of hAQP1, and contributes information on water channel behavior under osmotic challenges and the discovery of new inhibitors.
authors.affiliation: Laboratorio de Biomembranas, Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, 7º Piso, C1121ABG Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina. mozu@fmed.uba.ar
authors.forename: Marcelo
authors.initials: M
authors.lastname: Ozu
authors.forename: Ricardo A
authors.initials: RA
authors.lastname: Dorr
authors.forename: M
authors.initials: M
authors.lastname: Teresa Politi
authors.forename: Mario
authors.initials: M
authors.lastname: Parisi
authors.forename: Roxana
authors.initials: R
authors.lastname: Toriano
mesh_terms: D000818:Animals; D051398:Aquaporin 1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D005665:Furosemide / Q000494:pharmacology*; D006801:Humans; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D009995:Osmosis / Q000187:drug effects; D049994:Sodium Potassium Chloride Symporter Inhibitors / Q000494:pharmacology*; D014867:Water / Q000378:metabolism*; D014982:Xenopus laevis / Q000378:metabolism*
chemical_list: D049994:Sodium Potassium Chloride Symporter Inhibitors; D014867:Water; D051398:Aquaporin 1; D005665:Furosemide